//找出1-100之间3的倍数
let count = 0;
for (let i = 0; i < 100; i++) {
    if (i % 3 === 0) {
        document.write(`${i}&nbsp;&nbsp‘`);
        count++;
        if (count % 10 === 0) {
            document.write('<br/>');
        }
    }

}